St. Johnsbury Caledonian. [volume] (St. Johnsbury, Vt.) 1867-1919, 1887-09-01
THE BLIGHT OF APPLE TREES.

4 Its Cause and Suggestions to Treat
ment.
In midsummer IL letter was sent from
s ths office to the Agricultural Expert
3 thent station at Geneva, N. Y, enclOs-
4 big some of the blackened leaves and
wigs taken from apple trees in this
place with enquiries as to the cause OF
the blight and the remedy, if any.
+ People who have watched their fruit
trees gradually or rapidly dying in this
manner will be interested in the fol-
owing reply just received from DR.. j.
4 q. Arthur, bOtanist of the institution,
but who just now has been called to be
Z bOtanist to Purdue university, La Fay
& bite, Indiana:
There is a blight of apple trees which
attacks the twigs and smaller branch
s. es, turning the leaves brown, and kill
ing all the parts as far as it extends.
The attack may be light, merely dot
ling the head of the tree with the dead
4 and blasted twigs, or it may be severe
4 Enough to destroy the larger part of
he foliage, or in very unusual cases
+ Bhe whole tree.
This kind of blight is not associated
with any kind of insect, or any kind of
i fungOus disorder visible to the naked
bye. 1t is, in fact, due to the presence
pf astOnishingly small germs, which
{ multiply inside the twigs and branches
s with such deadly effect that any part
4 Of the tree which is affected speedily
dies. The germs do not start from any
internal imperfectiOn or debility of the
branches, but find entrance from the
air. 1t is not an easy matter, however,
4 for these minute bodies to effect an en-
trance, for the bark of the tree is quito
imperviOus unless it be punctured or
cut by accident, and the leaves, for
some reason not yet discovered, will
not support the germs. The most COM
mon and chief means of attack is
4 through the delicate surface of the tips
of the growing shoots, and through
the centre of the flowers. 1t will usu-
4 ally require but brief examination to
find among the dead branches plenty
advanced in development beyond the
stage of full bloom, and it is through
these that the blight germs found en-
trance to that part of the tree.
remedy an attack of blight of this kind :
1t is sufficiently evident from the ex-
T PLANTATION already given that to pre-
vent the germs entering the tree is a
difficult matter, and, in fact, up to the
present time there has been no means
found for accomplishing it. An indi-
rect method looking toward this result
is to give such cultivation to the Or
chard that the annual growth shall be
4 slow and uniform, and in consequence
there will be the least possible expos
urc of tender surface on the growing
twigs.
The only remedy after the disease
shows itself in the tree is to cut of
land as a matter of precaution to burn)
the dying branches, being sure to cut a
foot or so below the dead part. This
practice is the most desirable when the
disease threatens to be severe in light
attacks the disease may be left to run
its course. 1t is not common for the
disease germs in the tree to survive
the winter, but in case of another at
tack the succeeding summer they come
from the air as in the first instance.
To know what causes the disease
and the course of development, is an
advance upon the state of ignorance
which existed a few years ago, and
may be taken as an indication that YET
further investigation may provide more
effective means of combating the dis
ease.